Stephen Erickson was just 13 years old when he fell in love with planes — inside a Boston movie theater. He was watching aircraft mechanic Joe Patroni, played by George Kennedy in the original “Airport” movie, extricate a Boeing jet full of worried passengers from a snowdrift. “That moment was the spark that changed my life,” he says. “I wanted to build aircraft engines.” He enrolled in a technical school and joined GE Aviation, where he has become an ace test engineer — a real-world Patroni.
Now 59, Erickson normally works at a GE Aviation plant in Lynn, Massachusetts. But in September, he moved to Prague on a special assignment: getting GE’s first 3D-printed commercial aircraft engine ready for its inaugural test, and then firing it up for the very first time. Last week, Erickson was in his element, attaching the final sensors to the engine, called Advanced Turboprop, or ATP. He worked methodically inside a bunkerlike test cell located on the snowy outskirts of the Czech capital. “There is no engine like it in the world,” Erickson said.
The engine passed the first test last Friday.
“This is a pivotal moment,” says Paul Corkery, general manager of the Advanced Turboprop program. “We now have a working engine. We are moving from design and development to the next phase of the program, ending with certification.”
Some 400 GE designers, engineers and materials experts in the Czech Republic, Italy, Germany, Poland, the U.S. and elsewhere spent the last two years developing the engine. More than a third of the ATP is 3D-printed from a special titanium alloy.
3D printing and dozens of other new technologies used for the first time in a civilian turboprop engine allowed the team to combine 855 separate components into just 12, shave off more than 100 pounds in weight, improve fuel burn by as much as 20 percent, give it 10 percent more power and simplify maintenance. “This engine is a game changer,” Corkery says.
For example, the designers included components in the engine’s compressor that were originally developed for supersonic engines. These parts, called variable vanes, will allow it to fly efficiently even in thin air at high altitudes. They also developed a new digital way to control the turboprop engine that will enable pilots to fly it like a jet, with just a single lever instead of three. How easy is it to fly with the new controls? “I would use the phrase ‘revolutionary simplicity,’” says Brad Thress, senior vice president of engineering at aircraft maker Textron Aviation. Textron’s new Cessna Denali will be the first plane to use the engine.
During his three decades at GE Aviation, Erickson has been involved in testing the company’s workhorse engines, including the T700 engine for Black Hawk helicopters and the T408 engine for the Super Stallion and King Stallion, America’s most powerful helicopter. But he says that in his career he hasn’t seen “anything like the ATP.”
Erickson’s long and tall test cell in Prague is one of several attached to GE Aviation’s factory here. Employees at the plant assemble and service GE turboprop engines for commuter, agricultural and even acrobatic planes flying on six continents, like the L-410 and the Thrush crop duster.
Workers at the plant spent the fall assembling the first ATP engine in a special room next to the test cell. In early December, the team carefully loaded the new engine onto a special cart and moved it across the hall into the test cell. By then the group included engineers from the Italian aviation company Avio Aero, which is already designing and printing parts for jet engines. GE acquired Avio Aero in 2013.
Inside the cell, the team connected the ATP to a boxy water brake, which simulates the torque caused by the propeller, and connected the engine to tubes supplying air, fuel and oil and removing exhaust.
They also attached hundreds of wires, tubes and cables to the engine, leading to sensors located in gray, metal cabinets along the wall. The sensors gather information about vibrations, torque, thrust and other inputs. The test cell also has numerous cameras that keep an eye on fuel and oil leaks.
Data from the sensors travel to large computer servers located one floor above the cell. The servers already hold information GE gathered from testing individual components of the engine over the last year. For example, the ATP team tested the compressor with the variable vanes at a special custom-built rig located at the Technical University of Munich. “We can push it to stalling point and test the entire operating range,” Rudolf Selmeier, one of the GE engineers involved in running the tests, said.
GE plans to build a total of 10 test ATP engines and open five more test cells. The company will use them to run a battery of tests before the engine can be certified for flight by government authorities, including altitude, performance and high-vibration testing. GE will also test the engine on the wing of a flying “test bed” later this year and plans to certify it for passenger flight over the next two years.
By last Friday morning, everything was ready for the first engine’s big moment. The team secured the test cell’s thick steel-and-concrete doors and decamped into a control room upstairs. They watched the engine spin to life on a bank on large screens, starting a new chapter in aviation history.